1. Field of the Invention
The present invention relates to a process for treating alkaline waste liquid which contains ionic and/or colloidal substances.
2. Related Art
Nuclear fuels such as uranium or thorium remain in the waste liquid drained during the processing of nuclear fuels. Methods using adsorbent such as gelled persimmon tannin, chelating resin, or hydrated titanium oxide are hitherto known as the waste treatment processes for the waste liquids of this kind,
With such waste liquids, however, uranium and thorium may exist not only in the ionic state but also in the form of minute colloidal substances. The ionic substances can be adsorbed and removed by the aforesaid conventional methods, but the colloidal substances cannot be successfully removed.
The applicant of this application has previously developed a novel waste treatment process using tannin, which was disclosed in Japanese Patent Application No. 2-2051. This copending application, which is not published yet, describes a process comprising the steps of dissolving a tannin in a solution containing material to be removed, adding an aldehyde to the solution and further adding ammonia to the solution to produce a precipitate having the tannin as a principal constituent and capturing the material to be removed on the precipitate. This treatment process is applicable to the treatment of the waste liquids in which uranium and thorium exist even in colloidal state. However, the process is rather complicated, for which reason improvement has been desired.